Knitted wire carriers are commonly used in the area of automotive weather seals, among other uses. Generally, such carriers consist of a continuous wire weft formed into a serpentine propeller pattern with rounded ends. The ends join together a series of approximately propeller-shaped or parallel weft segments (limbs) upon which a plurality of warp threads is knitted. This type of knitted wire carrier is used as a reinforcing frame for elastomeric seals that are produced by extrusion and other continuous-forming processes. Such seals are often used in automotive and other vehicle applications.
The manufacture of extruded weather seals involves the application of substantial forming pressure to the wire carrier. The warp threads in many examples are applied in clusters or strips, all of which are designed to maintain the serpentine (also informally termed “zig-zag”) wire weft the appropriately spaced orientation during the formation process. Absent these warp threads, the wire would tend to stretch and deform, generating an inferior or unusable finished seal product.
Wire carriers are an efficient mechanism for constructing a weather seal. However in certain application they experience excess compressibility or elongation—for example when the weather seal is fitted around a tight-radius corner. That is, the seal compresses or stretches and does not maintain the desired, conforming profile on the door, trunk, etc.
One prior art approach to reduce excess compressibility and elongation in weather seals is to reinforce the elastomeric seal element with a perforated metal (e.g. low carbon steel) strip. Such a strip 100 in an unfolded orientation is shown by way of background in FIG. 1. The specific geometry of the strip 100, as well as its overall width, length, thickness, are highly variable depending on the weather seal application and desired performance characteristics. In an embodiment, the strip 100 has an overall width SW of approximately 20-65 millimeters and a thickness (perpendicular to the page of the figure) of between approximately 0.3 and 0.76 millimeters (e.g. 0.45 millimeters). The exemplary strip 100 includes a series of regular edge slots 110, formed along each opposing edge, having a width WS of between approximately 1 and 3 millimeters, and a series of central slots 120 offset from the edge slots 110 as shown. The strip can be formed into a desired shape (e.g. folding, stretching, etc.) and molded into a weather seal. The completed seal is capable of bending around sharp corners without significant puckering, wrinkling, compression or elongation.
Disadvantageously, this perforated, low-carbon steel strip requires a large quantity of sheet metal to produce (weight-per-unit-of-length) and employs involved stamping or cutting equipment, dies, etc.